Domestication and the first steps of sunflower breeding date back more than 4000 years. As an interesting crop to humans, sunflower underwent significant changes in the past to finally find its place as one of the most significant oil crops today. Substantial progress has already been made in understanding how sunflower was domesticated. Recent advances in molecular techniques with improved experimental designs contributed to further understanding of the genetic and molecular basis underlying the architectural and phenotypic changes that occurred during domestication and improvements in sunflower breeding. Understanding the domestication process and assessing the current situation concerning available genotypic variations are essential in order for breeders to face future challenges. A review of the tools that are used for exploring the genetic and genome changes associated with sunflower domestication is given in the paper, along with a discussion of their possible implications on classical sunflower breeding techniques and goals.

Broomrape is a root parasitic plant causing yield losses in sunflower production. Since sunflower is an important oil crop, the development of broomrape-resistant hybrids is the prime breeding objective. Using conventional plant breeding methods, breeders have identified resistant genes and developed a number of hybrids resistant to broomrape, adapted to different growing regions worldwide. However, the spread of broomrape into new countries and the development of new and more virulent races have been noted intensively. Recent advances in sunflower genomics provide additional tools for plant breeders to improve resistance and find durable solutions for broomrape spread and virulence. This review describes the structure and distribution of new, virulent physiological broomrape races, sources of resistance for introduction into susceptible cultivated sunflower, qualitative and quantitative resistance genes along with gene pyramiding and marker assisted selection (MAS) strategies applied in the process of increasing sunflower resistance. In addition, it presents an overview of underutilized biotechnological tools, such as phenotyping, -omics, and genome editing techniques, which need to be introduced in the study of sunflower resistance to broomrape in order to achieve durable resistance.

Winter oilseed rape (WOSR) production is dependent on weather conditions, but is also characterized by low nitrogen (N) use efficiency. The objectives of this study were to: (i) evaluate sources of variability for the seed yield and oil content of four rapeseed cultivars under the influence of three sowing dates (SD trial) and five nitrogen dosages (N trial) during four growing seasons; (ii) understand year-related interactions and the effect of climatic variables in different growth stages; and (iii) assess the presence of interactions cultivar by year (C × Y) and treatment by year (T × Y). Six climatic factors were observed, during germination, overwintering, budding, flowering and ripening. The mixed effect split-plot analysis of variance was used, as well as factorial regression models. The C × Y interaction was the most important for the oil content in both trials. The precipitation at budding stage (75.8%), relative air humidity at overwintering (63.3%) and flowering stage (53.0%) accounted for the highest proportion of T × Y interaction for the seed yield, as well as precipitation at flowering (92.0%) and ripening (85.0%) for the oil content. Water availability was the main determinant of the seed yield and/or oil content accompanied with cooler temperatures during the seed development. The study successfully dissected the effect of year-related climatic variables on the agronomical traits in winter rapeseed. Based on this, appropriate agronomic practices can be applied at specific growing stages to ensure a high seed and oil yield.

Hybrid breeding in sunflowers based on CMS PET1 requires development of restorer lines carrying, in most cases, the restorer gene Rf1. Markers for marker-assisted selection have been developed, but there is still need for closer, more versatile, and co-dominant markers linked to Rf1. Homology searches against the reference sunflower genome using sequences of cloned markers, as well as Bacterial Artificial Chromosome (BAC)-end sequences of clones hybridizing to them, allowed the identification of two genomic regions of 30 and 3.9 Mb, respectively, as possible physical locations of the restorer gene Rf1 on linkage group 13. Nine potential candidate genes, encoding six pentatricopeptide repeat proteins, one tetratricopeptide-like helical domain, a probable aldehyde dehydrogenase 22A1, and a probable poly(A) polymerase 3 (PAPS3), were identified in these two genomic regions. Amplicon targeted next generation sequencing of these nine candidate genes for Rf1 was performed in an association panel consisting of 27 maintainer and 32 restorer lines and revealed the presence of 210 Single Nucleotide Polymorphisms (SNPs) and 67 Insertions/Deletions (INDELs). Association studies showed significant associations of 10 SNPs with fertility restoration (p-value < 10−4), narrowing Rf1 down to three candidate genes. Three new markers, one co-dominant marker 67N04_P and two dominant markers, PPR621.5R for restorer, and PPR621.5M for maintainer lines were developed and verified in the association panel of 59 sunflower lines. The versatility of the three newly developed markers, as well as of three existing markers for the restorer gene Rf1 (HRG01 and HRG02, Cleaved Amplified Polymorphic Sequence (CAPS)-marker H13), was analyzed in a large association panel consisting of 557 accessions.

Sunflower has been proposed as a potential crop model for an adaptation to a changing environment and special attention should be paid to testing hybrids under different environments. Additive main effects and multiplicative interaction model (AMMI) supplemented with genotype main effects and genotype by environment interaction effects (GGE) were used for dissection of genotype by environment interaction and evaluation of hybrids and testing environments. The research included 24 sunflower hybrids grown across twelve environments. AMMI analysis identified four significant interaction principal components (IPC), while in GGE biplot the first two IPCs accounted together for 44.59%. Environmental factors contributed the largest proportion in the total variation of seed yield (67.40%), followed by interaction and genotypes. High yielding hybrids H1, H14 and H11 showed specific adaptation to environments E10 and E1, respectively. The average environment coordination (AEC) view of GGE biplot indicated H17 as the most desirable genotype regarding seed yield. From the results of this study it can be concluded that MET trials are important not just for evaluation of stability and choosing the most stable genotypes, but also the genotypes that will perform well in low yielding environments and be able to take advantage of the favourable environmental conditions.

Three hybrid combinations obtained by crossing six winter rapeseed cultivars were analyzed for the impact of genes with additive and dominant effects and their interactions with inheritance of plant height and first lateral branch height. The linkage among the expected progeny means was checked using the scaling test method (Mather, 1949), while the estimates of genetic effects and mode of inheritance was made by the Generation Mean Analysis (Mather and Jinks, 1982). The additive dominant model did not prove adequate for plant height in all three crosses, and for first lateral branch height in the second and third cross. The inadequacy of the model showed epistatic gene effects were also of large importance in the inheritance of these traits. Duplicate epistasis for plant height inheritance was found in all three cross combinations and for inheritance of height of the first lateral branch in second and third cross combination. However, it should be emphasized that duplicate epistasis among dominant positive genes occurred on plant height inheritance in C1 and C3, and on inheritance of first lateral branch height in C3. Duplicate epistasis among dominant negative genes occurred in C2 on the mode of inheritance of both traits. [Projekat Ministarstva nauke Republike Srbije, br. TR-31025]

The research describes the field comparison of 81 decorative sunflower genotypes. In order to assess genetic diversity of sunflower genotypes the studies were conducted in the field conditions during 2010-2015 at the Institute of Field and Crops, Novi Sad, Serbia. The genetic diversity of species Helianthus annuus L. has enabled the breeding work in the direction of the decorating and plant landscaping. Depending on the qualitative and quantitative characteristics, production of decorative sunflowers can be divided into three directions. The first line is for the production of cut flowers, the second one is for garden production and the third line is for the production of pot plants. The direction of production dictates the main breeding objectives, which may include: plant architecture, the color of ray and disc flowers and duration of flowering. Investigation of the genetic variability of ornamental sunflowers relies on quantitative traits of which the greatest variability was observed in branching and plant height, which are also the most important qualities for production. The quantitative characteristics of decorative sunflowers have been examined on the basis of 81samples.

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